“I have a theory on concussions,” (Carlyle) said. “I think the reason there’s so much more of them obviously the impact and the size of the equipment and the size of the player — but there’s another factor: everyone wears helmets, and under your skull when you have a helmet on, there’s a heat issue.

“Everyone sweats a lot more, the brain swells. The brain is closer to the skull. Think about it. Does it make sense? Common sense?” said Carlyle, who said he’d never talked to a doctor about his premise, which he was introduced to by Jim Pappin, the former Leaf who also played his career helmet free.

“I don’t know if it’s true, but that would be my theory. Heat expands and cold contracts. The brain is like a muscle, it’s pumping, it swells, it’s a lot closer to the outside of the skull.”

Side-stepping some obvious jokes: Helmets do not cause concussions, and the brain does not swell during normal physical exertion. This is not opinion. This is science. Check WebMD or ask virtually any medical professional if you don't believe it. Carlyle, for the record, played in NHL the from 1976-93 without wearing a helmet.

The reason this is an issue: Leafs star Joffrey Lupul is out with an injury neither Carlyle nor the team will call a concussion, despite the fact that he left Thursday's game after getting sandwiched between two Flyers and having his head bounce off one of their shoulders. Lupul clearly was dazed and jelly-legged after the collision, and he's currently day-to-day with an "upper-body injury." Okey dokey.

Carlyle, speaking about Lupul, said "concussion" was "a bad word," and that it shouldn't be used until "we’re 100 percent sure on any of the situations."

“Until you know exactly what it is, I don’t think you should make any statements," Carlyle continued. "Everyone saw the hit, he got squeezed out, he was dazed and didn’t feel very good, so we sent him for an examination (Friday) morning and they just said he was day-to-day.”

On some level, waiting for certainty on a concussion diagnosis isn't a terrible idea—assuming that everyone involved errs on the side of caution. Considering Carlyle's pseudoscience sermon, and the organization's problematic recent history on the subject, it's fair to question whether that's the case. Diagnoses and treatment, thankfully, aren't up to the coach, but he's an influential figure with some seriously misguided views.

Lupul, for the record, has nine goals and five assist in seven games since returning from a broken forearm that sidelined him for 25 games. Toronto opened Saturday in sixth place in the Eastern Conference.